rtc: add m41t62 support to rtc-m41t80 driver

Compared to the other supported chips, the m41t62 uses a different
register to set the square wave frequency.
Signed-off-by: Daniel Glockner <dg@emlix.com>
Cc: Chris Zankel <chris@zankel.net>
Cc: David Brownell <david-b@pacbell.net>
Cc: Alessandro Zummo <a.zummo@towertech.it>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

drivers/rtc/Kconfig

@@ -225,11 +225,11 @@ config RTC_DRV_PCF8583
 	  will be called rtc-pcf8583.
 
 config RTC_DRV_M41T80
-	tristate "ST M41T65/M41T80/81/82/83/84/85/87"
+	tristate "ST M41T62/65/M41T80/81/82/83/84/85/87"
 	help
 	  If you say Y here you will get support for the ST M41T60
 	  and M41T80 RTC chips series. Currently, the following chips are
-	  supported: M41T65, M41T80, M41T81, M41T82, M41T83, M41ST84,
+	  supported: M41T62, M41T65, M41T80, M41T81, M41T82, M41T83, M41ST84,
 	  M41ST85, and M41ST87.
 
 	  This driver can also be built as a module. If so, the module

drivers/rtc/rtc-m41t80.c

@@ -64,10 +64,12 @@
 #define M41T80_FEATURE_BL	(1 << 1)	/* Battery low indicator */
 #define M41T80_FEATURE_SQ	(1 << 2)	/* Squarewave feature */
 #define M41T80_FEATURE_WD	(1 << 3)	/* Extra watchdog resolution */
+#define M41T80_FEATURE_SQ_ALT	(1 << 4)	/* RSx bits are in reg 4 */
 
 #define DRV_VERSION "0.05"
 
 static const struct i2c_device_id m41t80_id[] = {
+	{ "m41t62", M41T80_FEATURE_SQ | M41T80_FEATURE_SQ_ALT },
 	{ "m41t65", M41T80_FEATURE_HT | M41T80_FEATURE_WD },
 	{ "m41t80", M41T80_FEATURE_SQ },
 	{ "m41t81", M41T80_FEATURE_HT | M41T80_FEATURE_SQ},
@@ -393,12 +395,15 @@ static ssize_t m41t80_sysfs_show_sqwfreq(struct device *dev,
 {
 	struct i2c_client *client = to_i2c_client(dev);
 	struct m41t80_data *clientdata = i2c_get_clientdata(client);
-	int val;
+	int val, reg_sqw;
 
 	if (!(clientdata->features & M41T80_FEATURE_SQ))
 		return -EINVAL;
 
-	val = i2c_smbus_read_byte_data(client, M41T80_REG_SQW);
+	reg_sqw = M41T80_REG_SQW;
+	if (clientdata->features & M41T80_FEATURE_SQ_ALT)
+		reg_sqw = M41T80_REG_WDAY;
+	val = i2c_smbus_read_byte_data(client, reg_sqw);
 	if (val < 0)
 		return -EIO;
 	val = (val >> 4) & 0xf;
@@ -419,7 +424,7 @@ static ssize_t m41t80_sysfs_set_sqwfreq(struct device *dev,
 {
 	struct i2c_client *client = to_i2c_client(dev);
 	struct m41t80_data *clientdata = i2c_get_clientdata(client);
-	int almon, sqw;
+	int almon, sqw, reg_sqw;
 	int val = simple_strtoul(buf, NULL, 0);
 
 	if (!(clientdata->features & M41T80_FEATURE_SQ))
@@ -440,13 +445,16 @@ static ssize_t m41t80_sysfs_set_sqwfreq(struct device *dev,
 	almon = i2c_smbus_read_byte_data(client, M41T80_REG_ALARM_MON);
 	if (almon < 0)
 		return -EIO;
-	sqw = i2c_smbus_read_byte_data(client, M41T80_REG_SQW);
+	reg_sqw = M41T80_REG_SQW;
+	if (clientdata->features & M41T80_FEATURE_SQ_ALT)
+		reg_sqw = M41T80_REG_WDAY;
+	sqw = i2c_smbus_read_byte_data(client, reg_sqw);
 	if (sqw < 0)
 		return -EIO;
 	sqw = (sqw & 0x0f) | (val << 4);
 	if (i2c_smbus_write_byte_data(client, M41T80_REG_ALARM_MON,
 				      almon & ~M41T80_ALMON_SQWE) < 0 ||
-	    i2c_smbus_write_byte_data(client, M41T80_REG_SQW, sqw) < 0)
+	    i2c_smbus_write_byte_data(client, reg_sqw, sqw) < 0)
 		return -EIO;
 	if (val && i2c_smbus_write_byte_data(client, M41T80_REG_ALARM_MON,
 					     almon | M41T80_ALMON_SQWE) < 0)